Apparatus for extruding metal tubing



Nov. 19, 1968 Filed Oct. 14, 1966 A. M. MURPHY ETAL 3,411,337

APPARATUS FOR EXTRUDING METAL TUBING 5 Sheets-Sheet 1 I l 1 I INVENTORS ALFRED M. MURPHY THOMAS P. LONG NICKOLAS A. WAGNER CARI. M. FILAK Filed Oct. 14, 1966 5 Sheets-Sheet 2 CARL M. FI'LAK BY I J/Zm%,%%

Nov. 19, 1968 A. M. MURPHY ETAL 3,411,337

APPARATUS FOR EXTRUDING METAL TUBING 5 Sheets-Sheet 3 Filed Oct. 14, 1966 INVENTORj ALFRED M. MURPHY THOMAS F? LONG NICKOLAS CARL A. WAGNER M. FILAK Nov. 19, 1968 A. M. MURPHY ETAL 3,411,337

APPARATUS FOR EXTRUDING METAL TUBING 5 Sheets-Sheet 4 Filed Oct. 14, 1966 INVENTORS MURPHY LONG ALFRED M.

THOMAS F.

NICKOLAS A. WAGNER CARL M. FILAK Nov. 19, 1968 A. M. MURPHY ETAL 3,411,337

APPARATUS FOR EXTRUDING METAL TUBING 5 Sheets-Sheet 5 Filed Oct. 14, 1966 F; E10. 48 I28 I20 50 I36 WW ATTORNEYS United States Patent Oifice 3,411,337 Patented Nov. 19, 1968 3,411,337 APPARATUS FOR EXTRUDING METAL TUBING Alfred M. Murphy and Thomas P. Long, Richmond, Va., and Nicholas A. Wagner and Carl M. Filak, Chester, Va., assignors to Reynolds Metals Company, Richmond, Va., a corporation of Delaware Filed Oct. 14, 1966, Ser. No. 586,837 14 Claims. (Cl. 72-264) ABSTRACT OF THE DISCLOSURE A traveling piercing mandrel has an enlarged base which fits within a slot in a fixed dummy block, whereby the mandrel is securely locked therein but may be quickly replaced. The shapes of the mandrel base and slot allow the mandrel base to be slid freely through the slot when it has a certain angular orientation with respect thereto. At the bottom of the slot, the mandrel may be rotated 90, camming it back into a recess and locking it in a position to pierce and extrude. Rear and front surfaces of the mandrel base and slot are conical so as to keep the mandrel centered during piercing and extruding.

This invention relates to apparatus for extruding metal tubing wherein a fixed or French mandrel is secured to an extrusion press ram. More particularly, the invention is concerned with novel systems for securing the mandrel to the ram.

In copending application Ser. No. 456,107, filed May 17, 1965, applicants Alfred M. Murphy and Carl M. Filak disclose a system which, by providing for a two-stroke extrusion cycle, enables an extrusion press whose mandrel cannot move independently with respect to the ram to pierce, as well as extrude, a metal billet.

In this extrusion cycle, a centering projection is mounted on the front of the ram, and the ram advanced into the container, where the projection fits into a passage in a dummy block and the dummy block advances with the ram to crush the metal billet. (As used herein, the terms front, forward, and the like will refer to the direction in which the metal is being extruded, while the terms rear, backward, and the like will refer to the opposite direction.) The crushing upsets the billet against the container and die, thereby expelling air from the container, but ceases before metal is extruded through the die orifice. Then the ram is retracted from the rear of the container, leaving the dummy block adhered to the rear face of the billet, and the projection is replaced by a piercing mandrel. The ram is advanced again, so that the piercing mandrel mounted thereon pierces a hole along the axis of the billet and becomes disposed concentrically in the die orifice. Continuing its forward movement, the ram contacts the dummy block, which in turn compresses the rear of the billet, thereby extruding it through the annular passage defined by the die orifice and the mandrel to form tubing. To complete the cycle, the container is cleared of the dummy block and billet butt, the ram is retracted, and the mandrel is replaced with the centering projection.

Such a system places a premium upon centering the mandrel with respect to the die orifice during all phases of the extrusion cycle. The piercing operation tends to force the mandrel back against the ram, while at the same time tending to deflect it by rotating it about its connection with the ram. Such deflection is undesirable because the mandrel must be centered in the die orifice for the extrusion of tubing of uniform wall thickness. During the initial part of the extruding operation, the mandrel similarly is urged back against the ram because of the friction between the billet and the mandrel. When a substantial portion of the billet has been extruded, however, this friction decreases until it is overridden by the force of the flow of metal approaching the die orifice, which metal is moving much faster than the mandrel. At this point the mandrel tends to be pulled away from the ram. Any system which is to ensure proper alignment of the mandrel with respect to the die orifice must be able to take all of these forces into account. Not only does deflection of the mandrel affect the dimensions of the tubing being extruded, but it also cumulatively wears the engaging surfaces of the mandrel and ram to promote even greater deflection during future extruding operations.

On the other hand, such a two-stroke piercing and extruding system requires that the mandrel and centering projection be readily interchangeable, since time spent connecting and disconnecting such tooling is unproductive. These requirements of alignment and interchangeability have heretofore been considered to be at odds with each other.

The purpose of the present invention is to provide for an extrusion press a novel system for securing the mandrel to the ram, whereby the mandrel can be disposed and miantained in proper alignment during the extrusion of metal tubing, yet can be rapidly and easily connected to or disconnected from the ram.

While the present invention is especially useful in connection with extrusion presses employing the two-stroke piercing and extruding cycle disclosed in the aforesaid application Ser. No. 456,107, it will be clear that it may also be used with other types of extrusion apparatus and processes where ease of mandrel connection and disconnection is sought.

For a better understanding of the invention, and of its details and other advantages, reference is now made to the accompanying drawings, which show, for purposes of illustration only, present perferred embodiments of the invention. In the drawings:

FIGURE 1 is an elevation view, partially in section, of a portion of an extrusion press extruding metal tubing;

FIGURE 2 is an elevation view, partially in section, of a portion of an extrusion press crushing a metal billet;

FIGURE 3 is a rear view of a ram head plate for an extrusion press;

FIGURE 4 is a transverse view, partially in section, of the ram head plate shown in FIGURE 3 and a mandrel for an extrusion press;

FIGURE 5 is a plan view of the ram head plate shown in FIGURES 3 and 4;

FIGURES -6 and 7 are elevation views, Partially in section, of a ram head base and the ram head plate and mandrel shown in FIGURE 4;

FIGURE 8 is a view similar to FIGURE 7, with the mandrel rotated through an angle of degrees;

FIGURES 9-11 are plan views, partially in section, of portions of the ram head base, ram head plate and mandrel shown in FIGURES 6-8, with the mandrel in different rotational positions.

FIGURE 1 shows a horizontal extrusion press extruding billet 15 to form metal tubing 17. Die assembly 20, shown at the right of FIGURE 1, is supported and held stationary by a front platen (not shown), which in turn is secured to the floor. In die assembly 20, die arm 21, which is mounted upon the front platen, supports die holder 22 and bolster 23. Die holder 22 supports die support ring 24 and die support ring backup 25. Die support ring 24 supports die 26, through which extrusion orifice 27 extends, and die backup 28. To restrain die 26 from forward movement, bolster 23 bears against die holder 22 and die support ring backup 25, which in turn bears against die support ring 24 and die backup 28, which in turn bears against die 26.

Container is urged forward by conventional hydraulic pistons and cylinders (not shown) so that its liner 32 forms a metal-tight seal with die support ring 24.

Ram head is connected to ram stem 42 by threaded stud 44, and, for convenience of manufacture, consists of two parts: ram head base 46 and ram head plate 48, which are secured together by socket-head cap screws 49. (The term ram means will be used herein to include ram head 40, ram 42, or both.)

Mandrel 60, which is secured to ram head 40 in a manner to be described hereafter in more detail, has a piercing nose 62, a relatively long, cylindrical male extruding surface 64, a bell-shaped flange 66 with conical front surface 68 and flat rear surface 70, a cylindrical stem portion 72, and an enlarged base 74. Male extruding surface 64 extends through the center of billet 15 and is disposed concentrically in die orifice 27, defining therewith an annular passage which determines the crosssection of tubing 17.

Dummy block 76, which is separate from ram head 40, has a partially conical internal passage 78 which mates with male extruding surface 64 and flange 66 of mandrel 60. As shown in FIGURE 1, the rear face of dummy block '76 abuts the front face of ram head plate 48, while the front face of dummy block 76 abuts the rear of billet 15.

In the extrusion operation shown in FIGURE 1, a hydraulic fluid is introduced into the ram cylinder, a part of the stationary rear platen, which is secured to the floor. This urges forward the ram and its stem 42. (The ram cylinder is not shown, but would be located. well to the left in FIGURE 1.) As ram head 40, mandrel 60, and dummy block 76 advance, billet 15 is extruded between male extruding surface 64 and die orifice 27 to form tubing 17. As mentioned previously, the advancing mandrel must be kept closely aligned with extrusion orifice 27 in order to produce tubing of uniform Wall thickness.

Regressing in the extrusion cycle, FIGURE 2 shows the billet-crushing operation. Crushing is effected by advancing the ram 42, ram head 40, and dummy block 76, with crushing snub or projection 80 being used in place of mandrel 60. Crushing snub 80, although similar to mandrel 60 in having bell-shaped flange 82 with conical front surface 83 and flat rear surface 34, and a cylindrical stem portion 85, has only an abbreviated nose 86 protruding but a short distance from the front of dummy block 76, and also has a somewhat different enlarged base 88. (The shape of snub base 88 and the man ner in which snub 80 is attached to ram head 40 will be described hereinafter in greater detail.) Snub nose 86 produces a small indentation at the center of the rear face of the crushed billet.

As shown in FIGURES 4 and 6-11, enlarged base 74 of mandrel 60 has a conical front surface 90, a cylindrical side surface 92, and rear surface 94 which is partly conical, as shown at 96, and partly flat, as shown at 98. Two notches are cut into opposite sides of enlarged mandrel base 74. Each notch 100 is defined by two flat walls 102 and 104 intersecting at an obtuse angle, as shown best in FIGURES 8, 9, and 11. The intersection of walls 102 and 104 is slightly forward of the intersection of conical front surface 90 and cylindrical surface 92, with forward wall 102 being tangent to the surface of stem 72 and rearward wall 104 intersecting cylindrical surface 92.

The rear face of ram head plate 48 has two projections separated by channel 111 and having outer edges concentric with the periphery of ram head plate 48. Ram head base 46 has a mating front surface with a vertical rib (not visible) and rim 112. Rim 112 is almost annular, but terminates at the top of the front face of ram head base 46 to correspond to projections 110 on ram head plate 48. Ram head base 46 and ram head plate 48 are secured together before ram head base 46 is secured to ram stem 42 by stud 44, with projections 110 fitting closely Within rim 112 and two dowel pins 114 being inserted in corresponding recesses in the front face of ram head base 46. Four socket-head cap screws 49 extend through holes in ram head base 46 into threaded recesses 116 in the rear of ram head plate 48.

When secured together in the manner just described, and attached to ram stem 42 by means of threaded stud 44, ram head base 46 and ram head plate 48 define vertical slot 120 extending radially into ram head 40. Going radially inward, slot 120 is of uniform cross-section until it reaches a region near the axis of ram head 40 where the front face of ram head base 46 has a recess 122 with conical wall 124 and fiat bottom 126.

Except for this recess 122 and the annular rim 100 and rib previously mentioned, the front face of ram head base 46 is flat. Thus the rear of the portion of slot 120 having uniform cross-section is defined by the flat front face of ram head 46, while the rear of the enlarged portion of slot 120 in the region near the axis of ram head 40 is defined by recess 122.

The sides of both the enlarged and the unenlarged portions of slot 120 are defined by continuous, cylindrical, U-shaped wall 128. (The term cylindrical is used herein in its geometric sense to describe a surface traced by a straight line moving parallel to a fixed straight line.)

The front of the portion of slot 120 having uniform cross-section is defined by fiat surfaces 130. Radially inward of, or below, this portion of slot 120, the front of the enlarged portion of slot 120 is defined by conical seats 132, which are tangent to flat surfaces and terminate at their intersections with U-shaped wall 128.

Cylindrical, U-shaped wall 128 extends slightly forward of conical seats 132, where it intersects conical surface 134. Finally, a second continuous, cylindrical U- shaped wall 136 extends through ram head plate 48 to form a cavity extending between slot 120 and the front face of ram head plate 48.

To secure mandrel 60 to ram head 40 for a piercing and extruding operation, mandrel 60 is oriented as shown in FIGURE 4, with slots 100 vertical. Then, with its axis maintained parallel to the axis of ram head 40, mandrel 60 is lowered so that enlarged mandrel base 74 fits within slot 120, mandrel stem 72 fits in the cavity defined by walls 136, and rear surface 70 of bell-shaped flange 66 is spaced from the front face of ram head 48 by a distance equal to the depth of recess 122, as is shown in FIGURES 6 and 9. At this time, external surfaces of mandrel 60 are slideably engaged with internal surfaces of ram head 40 in the following manner: cylindrical surface 92 with the sides of U-shaped wall 128, rearwardmost wall 104 of each slot 100 with flat surfaces 130, forwardmost wall 102 of each slot 100 with the rear of the sides of the U- shaped wall 136, fiat portion 98 of rear surface 94 with the front face of a ram head base 46, and stem 72 with the sides of U-shaped wall 136.

When mandrel base 74 reaches the bottom of slot 120, it occupies the position shown in FIGURES 7 and 9, with the external surfaces of mandrel 60 in contact with internal surfaces of ram head 40 in the following manner: cylindrical surface 92 with the bottom of U-shaped wall 128, rearwardmost wall 104 of each slot 100 with flat surfaces 130, forwardmost wall 102 of each slot 100 with the rear of the sides of U-shaped wall 136, conical front surface 90 with conical surface 134, and stem 72 with the bottom of U-shaped wall 136. Rear surface 70 of hellshaped flange 66 is still spaced from the front face of ram head plate 48 by a distance equal to the depth of recess 122.

Next, mandrel 60 is locked and seated in its extruding position by being rotated 90 degrees about its axis. The rotational force is applied to extruding surface 64, either manually or by suitable mechanical manipulating apparatus. As mandrel 60 is rotated, conical surface 90 of mandrel base 74 comes into contact with the two conical seats 132, camming mandrel 60 to the rear, as shown in FIGURE 10. When the 90 degree rotation is completed, mandrel 60 is oriented as shown in FIGURES 1, 8, and 11, with the external surfaces of mandrel 60 in contact with internal surfaces of ram head 40 in the following manner: cylindrical surface 92 with the bottom of U- sha ed wall 128, conical front surface 90 with the two conical seats 132, conical rear surface 94 with conical recess 122, stem 72 with the bottom of U-shaped wall 136, and rear surface 70 of bell-shaped flange 66 with the front face of ram head plate 48.

Mandrel 60 is disconnected from ram head 40 by reversing the procedure just described, i.e., by rotating it 90 degrees so that slots 100 are vertical, pulling it forward, and withdrawing it upward from slot 120 while keeping its axis parallel to the axis of ram head 40.

When secured in the extending position, as shown in FIGURES l, 8, and 11, mandrel 60 experiences centering forces when it is urged either forward or backward with respect to ram head 40. If mandrel 60 is urged backward with respect to ram head 40, as occurs during the piercing operation and the first part of the extruding operation, conical rear surface 94 of enlarged mandrel base 74 bears against mating conical recess 122 in the front of ram read base 46, and flat rear surface 70 of bell-shaped flange 66 bears against the front face of ram head plate 48. If mandrel 60 is urged forward with respect to ram head 40, as occurs during the latter part of the extruding operation, conical front surface 90 of enlarged mandrel base 74 bears against mating conical seats 132 in ram head plate 48. In either case, conical front surface 68 of bell-shaped flange 66 bears against mating conical passage 78 in dummy block 76 to exert a further centering influence upon mandrel 60, as is shown in FIGURE 1.

Another advantage of the present invention is that during the extruding operation mandrel 60 cannot rise up in slot 120 unless it is rotated 90 degrees about its axis, so that mandrel 60 remains centered in the vertical direction during extruding. Further, even when mandrel 60 is rotated 90 degrees about its axis during extruding, as may infrequently result from erratic metal flow, it still cannot be pulled free of ram head 40, but can be withdrawn only by passage of its enlarged base 74 from the top of slot 120.

Base 88 of crushing snub 80 is not shaped like base 74 of mandrel 60, but instead is symmetric about the snub 80 axis. Front surface 140 of enlarged base 88 is conically shaped, being identical to its counterpart 90 of mandrel base 74. Cylindrical surface 142 of snub base 88 has the same diameter as, but in the direction of its axis is shorter than, its counterpart 92 of mandrel base 74. Consequently, the rear of the enlarged base 88 of crushing snub 80 does not extend backward within recess 122 in ram head base 46, and cannot serve to center snub 80 during crushing. However, snub nose 86 extends such a short distance forward of the front face of dummy block 76 that the centering force effected by rear surface 84 of bell-shaped flange 82 bearing upon the front face of ram head plate 48 has been found adequate to ensure that the indentation produced by snub nose 86 is in the center of the rear face of billet 15.

It should be noted that ram head 40 is made of two pieces, base 46 and plate 48, only because making slot 120 is thereby greatly facilitated. When ram head base 46 and ram head plate 48 are fitted together, rim 112 on the front face of the former surrounds projections 110 on the rear face of the latter. This minimizes the tendency of ram head plate 48 to yoke, or spread apart at the top of the slot, when it is under pressure.

It will be clear that the term tubing, as used herein, is not limited to hollow cylindrical members of circular cross-section, but includes hollow cylindrical members of various other cross-sections, such as elliptical, polygonal, and irregular, and also includes hollow cylindrical members designed to have non-uniform wall thickness.

While present preferred embodiments of the invention have been illustrated and described, it will be understood that the invention may be otherwise variously embodied and practiced, and, in particular, that the configuration and orientation of the various exemplary operative surfaces of the apparatus described herein may be modified, within the scope of the following claims.

What is claimed is:

1. In an extrusion press for extruding metal tubing, the combination comprising:

(A) ram means having at the front end a slot (1) extending radially into said ram means, and (2) at the axis of said ram means, enlarged in the direction of said axis; and

(B) a mandrel having (1) a relatively long, cylindrical male extruding surface, and (2) an enlarged base disposed rearwardly of said male extruding surface and of such a shape that (a) while in a first angular position about the axis of said mandrel, said mandrel base can be freely passed radially within the non-enlarged portion of said slot while said mandrel axis is maintained parallel to the axis of said ram, yet (b) when said mandrel base is within said enlanged portion of said' slot said mandrel can be rotated into a second angular position about its axis whereby said mandrel base cannot pass into said non-enlarged portion of said slot and said mandrel base is firmly locked within said enlarged portion with said mandrel axis aligned with said ram axis.

2. The apparatus of claim 1 wherein said enlarged portion of said slot extends rearward of the remainder of said slot.

3. The apparatus of claim 1 wherein the rear surface of said enlarged base of said mandrel and the rear surface of said slot in said ram means are at least partly conical, whereby said two surfaces mate when said mandrel is in said second angular position and said mandrel base is firmly locked within said enlarged portion of said slot.

4. The apparatus of claim 1 wherein the front surface of said enlarged base of said mandrel and the front surface of said slot in said ram means are at least partly conical, whereby said two surfaces mate when said mandrel is in said second angular position and said mandrel base is firmly locked within said enlarged portion of said slot.

5. The apparatus of claim 1 wherein said mandrel has disposed forwardly of said base and rearwardly of said male extruding surface an enlarged bell-shaped flange with a conical front surface and a rear surface, and said slot in said ram means is spaced from the front surface of said ram means a distance such that when said mandrel is in said second angular position and said mandrel base is firmly locked within said enlarged portion of said slot, said rear surface of said flange bears against said front surface of said ram means.

6. The apparatus of claim 5 wherein said rear sur face of said bell-shaped flange is flat.

7. The apparatus of claim '5 comprising further a dummy block having therein an axial passage which is conical at its rear end for mating with the conical front surface of said bell-shaped flange.

8. A mandrel for extruding metal tubing comprising, from front to rear:

(A) a relatively long, cylindrical male extruding surface,

(B) a bell-shaped flange with a conical front surface,

(C) a stem portion having a smaller cross-section than said flange, and

(D) an enlarged base having front and rear surfaces which are at least partly conical.

9. The mandrel of claim 8 wherein said bell-shaped flange has a flat rear surface.

10. The mandrel of claim 8 wherein two large notches are provided in opposite sides of said front surfaces of said enlarged base, the walls of each said notch being planar and intersecting at an obtuse angle.

11. The mandrel of claim 10 wherein the forwardmost wall of each said notch is tangent to the surface of said stem portion.

12. The mandrel of claim 11 wherein said enlarged base has a cylindrical surface between said front and rear surfaces, and the rearwardmost wall of each said notch intersects said cylindrical surface.

References Cited UNITED STATES PATENTS 1,285,328 11/1918 Neuberth 72264 1,330,489 2/1920 Neuberth 72264 1,331,169 2/1920 Swift et al 72266 1,859,990 5/1932 Schlenstedt 72264 CHARLES W. LANHAM, Primary Examiner.

K. C. DECKER, Assistant Examiner. 

